JSON-Schema add property to the item conditionally - json

Question

I have the following JSON data
[
{
"type": "social_media_profiles",
"data": {
"profiles": [
{
"key": "twitter",
"data": "username",
"field": "handle",
"label": "Tweet"
},
{
"key": "customLink",
"data": "abc",
"field": "url",
"label": "Click",
"color": {
"button": "red",
"text": "green",
"border": "yellow"
}
}
]
}
}
]
and following jsong schema
{
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "array",
"additionalProperties": false,
"items": {
"type": "object",
"required": ["type", "data"],
"additionalProperties": false,
"properties": {
"type": {
"type": "string",
"enum": [
"social_media_profiles"
]
},
"data": {
"type": "object"
}
},
"allOf": [
{
"if": {
"properties": {
"type": {
"const": "social_media_profiles"
}
}
},
"then": {
"properties": {
"data": {
"type": "object",
"required": ["profiles"],
"additionalProperties": false,
"properties": {
"profiles": {
"type": "array",
"items": {
"type": "object",
"required": ["data", "field", "key"],
"additionalProperties": false,
"properties": {
"data": {
"type": "string",
"description": "Data contains either profile url, handle id, etc."
},
"field": {
"type": "string",
"enum": ["url", "handle", "id", "tel"],
"description": "Type of field value."
},
"key": {
"type": "string",
"description": "Social media name used to distinguish each social network"
},
"label": {
"type": "string",
"description": "Label to display on the landing page"
}
},
"allOf": [
{
"if": {
"properties": {
"key": {
"const": "customLink"
}
}
},
"then": {
"properties": {
"color": {
"type": "object",
"additionalProperties": false,
"required": [],
"properties": {
"button": {
"type": "string"
},
"text": {
"type": "string"
},
"border": {
"type": "string"
}
}
}
}
}
}
]
}
}
}
}
}
}
}
]
}
}
I want to add new property color to the profiles item based on the condition when key of the item is customLink.
If key is not customLink then color property should not be there.
Validating the schema from https://www.jsonschemavalidator.net/ is giving error
Found 2 error(s)
Message: JSON does not match all schemas from 'allOf'. Invalid schema indexes: 0.
Schema path: #/items/allOf
Message: JSON does not match schema from 'then'.
Schema path: #/items/allOf/0/then/then
How can I append new property conditionally based on the sibling property value?

Answer 1

In your profiles.items schema, you defined additionalProperties: false.
additionalProperties depends on the properties defined in the same schema object, meaning that color would always be dissallowed.
You can separate out your concerns into "what properties are allowed", and "if their values are valid".
Moving the validation for the color object into profiles.properties allows you to maintain additionalProperties: false in that object level.
The schema values of the properties object are only applied to the instance location for the keys, if they exist (hence needing to use required to require that specific keys are... required).
Having simplified the condional section, you end up with a cleaner Schema.
You now only need to define the condition under which color is required, without worrying about what the value should look like.
Sudo code: if key is customLink, then require color, else dissallow color.
{
"if": {
"properties": {
"key": {
"const": "customLink"
}
}
},
"then": {
"required": [
"color"
]
},
"else": {
"not": {
"required": [
"color"
]
}
}
}
Using not, you can invert the validation result of the applied subschema, which is what you need to do when you want to define that a specific property is NOT allowed.
Here's a live demo to play with: https://jsonschema.dev/s/C9V6N
And for prosperity, here's the full schema, with one or two redundancies removed.
{
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "array",
"items": {
"type": "object",
"required": [
"type",
"data"
],
"additionalProperties": false,
"properties": {
"type": {
"type": "string",
"enum": [
"social_media_profiles"
]
},
"data": {
"type": "object"
}
},
"allOf": [
{
"properties": {
"data": {
"type": "object",
"required": [
"profiles"
],
"additionalProperties": false,
"properties": {
"profiles": {
"type": "array",
"items": {
"type": "object",
"required": [
"data",
"field",
"key"
],
"additionalProperties": false,
"properties": {
"data": {
"type": "string",
"description": "Data contains either profile url, handle id, etc."
},
"field": {
"type": "string",
"enum": [
"url",
"handle",
"id",
"tel"
],
"description": "Type of field value."
},
"key": {
"type": "string",
"description": "Social media name used to distinguish each social network"
},
"label": {
"type": "string",
"description": "Label to display on the landing page"
},
"color": {
"type": "object",
"additionalProperties": false,
"properties": {
"button": {
"type": "string"
},
"text": {
"type": "string"
},
"border": {
"type": "string"
}
}
}
},
"allOf": [
{
"if": {
"properties": {
"key": {
"const": "customLink"
}
}
},
"then": {
"required": [
"color"
]
},
"else": {
"not": {
"required": [
"color"
]
}
}
}
]
}
}
}
}
}
}
]
}
}